Composition containing body activated fragrance for contacting the skin and method of use

ABSTRACT

Described is a fragrancing composition having fragrancing components that are not activated until, e.g., application to the skin of a human. The composition is alkaline or (if anhydrous) capable of producing an alkaline pH when in contact with water, prior to application, and includes (1) a vehicle such that when the composition is in contact with water, prior to application, the composition is at an alkaline pH; and (2) at least one potential fragrance that is at least one compound having little or no odor in the alkaline composition but which, e.g., is hydrolyzed in a lower pH environment to produce compounds having a relatively strong aroma. Upon application of the alkaline composition to the skin surface, the strong buffering capacity of the skin (the surface of which has a normal pH of 5.5-7.0) neutralizes alkalinity of the composition (lowers pH) so as to restore normal skin surface pH; the potential fragrance is then hydrolyzed at the lower pH to release the compound having relatively strong aroma. The potential fragrance can be incorporated as a component of a transparent (clear) deodorant stick composition for application to human axillary regions, the fragrance being released after application to the body.

This application is a Continuation-in-Part application of applicationSer. No. 07/948,510, now U.S. Pat. No. 5,378,468 filed Sep. 22, 1992,the contents of which are incorporated herein by reference in theirentirety.

BACKGROUND OF THE INVENTION

The present invention relates to compositions, particularly compositionsfor contacting the skin (for example, skin care compositions or personalcare compositions), for producing fragrances. More particularly, thepresent invention relates to such compositions for contacting the skin,wherein the fragrance is formed (e.g., is released from a compoundforming a component of the composition) after application of thecomposition to the skin (that is, body activated fragrances).

It has been desired to provide personal care or skin care products whichhave components that produce a low level of odor, or are odorless, priorto application to the skin, but which components produce compounds thatare pleasant smelling (that is, provides a fragrance) after applicationto the skin (that is, delayed release of the fragrance). It is desiredto provide deodorant or antiperspirant stick products, hand lotions,baby lotions, baby powders, ointments, foot products, facial cleansers,body wipes, facial makeups, colognes, after-shave lotions and/or shavingcream having such components. It is also desired to provide personalcare or skin care products (particularly, a deodorant or antiperspirantstick product) that are clear or transparent, and have fragrancingcomponents that, prior to application to the skin (e.g., application tothe axillary regions), have a low degree of odor or are odorless, butbecome pleasant smelling after application.

Solid, transparent, gelled antiperspirant compositions, containing oneor more acidic reacting antiperspirant compounds, are known. Note eachof U.S. Pat. No. 4,154,816 to Roehl, et al., and U.S. Pat. No. 4,720,381to Schamper, et al., for example, the contents of each of which areincorporated herein by reference in their entirety. Each of these U.S.patents discloses solid, transparent or clear, antiperspirant gelledstick compositions including an antiperspirant metal compound (such asaluminum chlorohydrate), and alcohols (both monohydric and polyhydricalcohols), with sorbitol dibenzyl ether (DBMSA) utilized as a gellingagent. Such antiperspirant sticks gelled with DBMSA as the gelling agentare utilized as an alkaline or neutral media, but not as an acidicmedia, since even in the presence of small amounts of water DBMSAhydrolyzes in an acidic medium or will react with a reactive alcohol toform a different acetal. Such antiperspirant stick compositionscontaining DBMSA as the gelling agent are also known to includeconventional fragrances, which begin volatilizing at least as soon asthe product is formed.

There are also known antiperspirant sticks consisting largely of gelledalcoholic solutions of antiperspirant compounds, with the gelling agentbeing a sodium salt of a higher fatty acid, like sodium stearate.However, such sticks cannot contain the usual antiperspirant compounds,because the acidic reaction of these usual antiperspirant compoundscauses decomposition of the soap. To avoid this defect, alkalinereacting antiperspirant compounds were developed, like aluminum hydroxychloride-sodium lactate; but these alkaline reacting antiperspirantcompounds suffer from a disadvantage of having a poor antiperspiranteffect.

It is also known to delay release of a fragrance from a composition bymethods such as micro-encapsulation of the fragrance substance. However,a desired objective of a clear, transparent aqueous-glycol baseddeodorant stick cannot be obtained using such conventional methods ofachieving delayed release of fragrances, including micro-encapsulation.For example, standard methods of micro-encapsulating a fragrance oil ina water-soluble coating system will not work utilizing an aqueous-glycolbase, since the water in the deodorant stick base dissolves theprotective coating and prematurely releases the fragrance. Thus,water-soluble micro-capsules are not compatible with water/glycol basedformulations. Furthermore, a water-insensitive coating or micro-capsule,which is compatible with water/glycol based formulations (such aspH-sensitive or heat-sensitive micro- capsules), is not soluble in thewater/glycol formula and must therefore be used as a suspension of thesolid, micro-encapsulated fragrance in the liquid formula. As can beappreciated, suspensions of solids in clear liquids result in a formulawhich loses its transparent properties; suspensions are, at best,translucent, and cannot be absolutely clear.

Perfume compositions containing an acetal compound as the fragrancingsubstance are known. Thus, U.S. Pat. No. 4,424,146 to Willis, et al.discloses perfume compositions containing acetaldehyde ethyldihydrolinalyl (6,7-dihydrolinalyl) acetal, the acetal differing fromanalogous compounds in both odor quality and strength. This patentdiscloses that addition of the described acetal to various perfumecompositions imparts a greener, more lemony and floral character to theoriginal product.

U.S. Pat. No. 3,751,486 to Schleppnik, et al. discloses specificalkyl-substituted unsaturated acetals, useful in preparation andformulation of fragrance compositions such as perfumes and perfumedproducts due to the pleasing green, floral and woody aromas of theunsaturated acetals. This patent discloses that the acetals describedtherein have utility in cosmetic, detergent and bar soap formulations.

Neither of U.S. Pat. No. 4,424,146 or No. 3,751,486 discloses that thedescribed compounds can be utilized for delayed release of fragrance, orany mechanism for delayed release of fragrance upon application of,e.g., perfume compositions to the body; and these U.S. Patents do notdisclose use of the stated fragrance compounds in clear products (inparticular, clear deodorant or antiperspirant stick products).

U.S. Patent No. 3,479,297 to Rutzen, et al. discloses a room deodorantconsisting of 60%-80% by weight propellant; 20%-40% by weight solventand 0.5%-5% by weight active ingredient, the active ingredient being acyclic acetal or ketal of a monounsaturated aldehyde or ketone having atleast 3 carbon atoms and an aliphatic alcohol, the aliphatic alcoholbeing a 1,2-diol or 1,3-diol having 8-24 carbon atoms. This patentdiscloses that the cyclic acetal or ketal active ingredient isessentially odorless, but reacts within short periods of time withodiferous substances present in a room to form complexes neutral inodor, the active ingredients being sufficiently stable to retain theireffectiveness over a comparatively long period of time.

U.S. Pat. No. 3,479,297 discloses room deodorants (not body and/orunderarm deodorants or other personal care or skin care compositions)containing specific acetals or ketals which react with noxioussubstances. Such disclosure does not describe compounds which areodorless or of a low level of odor when applied (e.g., when applied toskin) and which are converted into pleasant smelling substances afterapplication.

Accordingly, it is still desired to provide compositions (e.g., personalcare or skin care products) having a delayed release of fragrance,especially a clear stick deodorant or antiperspirant product containingcomponents for providing a fragrance, so as to achieve a delayed releaseof fragrance. It is particularly desired to provide such product whereinthe fragrance is released after contact of the composition with skin(that is, a body activated fragrance).

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide a composition(e.g., a personal care product (such as a deodorant or antiperspirantfor axillary use or other personal care product), or skin care product,to contact the skin), having delayed release of fragrance (release offragrance after application of the composition), and method of usingsuch composition.

It is a further object of the present invention to provide a personalcare or skin care product having delayed release of fragrance, whereinthe release of fragrance does not occur until after contact with theskin (that is, wherein the fragrance is activated by the skin), andmethod of using such product.

It is a still further object of the present invention to provide apersonal care product or skin care product, in the form of a solution,powder, lotion, cream or other emulsion, or gelled stick (useful in, forexample, underarm deodorants or antiperspirants or other deodorantscontacting the body, or in hand lotions, baby powders, baby lotions,ointments, foot products, facial cleansers, body wipes, facial make-up,colognes, after-shave lotions and shaving creams), having at least onefragrancing component that is odorless or of a low level of odor priorto application to the human skin, but which changes into a pleasantsmelling substance (that is, which changes into a compound having astrong aroma) when in contact with the human skin.

It is a still further object of the present invention to provide apersonal care or skin care product, including a vehicle such that theproduct is useful in liquid roll-ons, sprays, aerosols and creamproducts applied to the human skin, having at least one fragrancingcomponent that is odorless or of a low level of odor when applied, butwhich changes into a pleasant smelling substance when in contact withthe skin.

It is a still further object of the present invention to provide atransparent (e.g., clear) deodorant or antiperspirant stick product witha delayed release of fragrance, the substance providing the fragrancebeing odorless or of a low level of odor prior to application but whichchanges into a pleasant smelling substance in contact with the humanskin.

The present invention is in part based upon the recognition byapplicants that human skin exhibits a "buffer capacity" which vigorouslymaintains a constant pH value. This buffer capacity is referred to as"the acid mantle". Human skin acts rapidly to neutralize acidic oralkaline insults outside this constant pH value.

Application of a high pH soap to the skin is an example of an alkalineinsult. A soap-based deodorant stick, which independently exhibits a pHof 9.5-10, is almost immediately neutralized after application to theskin by the "acid mantle" of the skin, to a pH of 8.2-8.3. Within sevenhours of application, underarm (axillary) skin pH at the site ofapplication is virtually restored to its original value of pH=5.5-7.0,due to the aforementioned buffer capacity of the skin.

Utilizing this recognition of the "buffer capacity" of the skin,applicants incorporate in a skin contact composition at least onecomponent ("potential fragrance") which maintains its integrity at a pHabove about 8.0 and which does not release fragrance at this alkalinepH, but which begins to lose its integrity as the pH lowers to a pH of8.0 or below and releases fragrance as skin pH returns to a normal,original (prior to application of the composition) value. Desirably, thepotential fragrance retains its integrity (does not release fragrance)at a pH above 7.5, but begins to lose its integrity at a pH of 7.5 andbelow to release fragrance.

Thus, applicants incorporate, in their skin care product, variouscomponents (molecules) which are chemically stable and practicallyodorless in an environment having a pH of 9.5-10 (for example, theenvironment of the aqueous/glycol soap-based deodorant stick), but whichbegin to hydrolyze at a pH of 8 and below (desirably, at a pH of 7.5 andbelow) to release the odorous portion of the molecule. Therefore, in a,e.g., deodorant base of pH=9.5-10, the component is a "potentialfragrance", capable of forming a compound having a pleasant scent (e.g.,upon lowering of the pH), yet itself being stable and relativelyodorless. Upon application to the skin, as the pH of the environment ofthe component lowers to a pH of 8 or less (desirably a pH of 7.5 orless), and as the skin pH lowers towards 5.5-7.0, fragrance is releaseddue to hydrolysis of the molecule releasing the odorous portion of themolecule; and as the skin pH lowers towards 5.5-7.0, more and morefragrance is released (e.g., over a roughly 7-12 hour period).

Accordingly, the present invention provides a composition, and method ofusing such composition, having a potential fragrance, the potentialfragrance only being activated after application of the composition to,e.g., the skin. The composition is an alkaline composition (e.g., has apH of 7.5 or greater, such as 8.0 or greater). The composition includesa vehicle so that the composition can be applied, and at least onepotential fragrance. The at least one potential fragrance has little orno odor, and is stable in the alkaline composition (e.g., in an alkalinesolution including water). However, upon lowering the pH of theenvironment of the potential fragrance, the potential fragrance reacts(e.g., is hydrolyzed) to release an odorous portion of the potentialfragrance, thereby providing a fragrance (e.g., a relatively strong,pleasant smelling aroma).

More specifically, the present invention provides a composition forcontacting human skin, having a body activated fragrance that isodorless or of a low level of odor when applied to the skin (e.g.,applied to the skin in an alkaline vehicle, having a pH greater than7.5) and which is converted by natural skin pH changes (due to thebuffer capacity of the skin) into a pleasant smelling substance, e.g.,by hydrolysis of the compound to release the odorous portion of themolecule, and method of using such composition.

Various specific materials which are stable at alkaline pH (e.g.,greater than pH=7.5), yet which undergo hydrolysis at a more acidic pHrange (e.g., at most pH=7.5) to produce pleasant odors, can beincorporated in the composition of the present invention. Specifically,and illustratively (without limitation), acetals or ketals, e.g., ofcarbonyl compounds, which are stable with respect to hydrolysis atalkaline pH (e.g., greater than pH=8.0; preferably, greater thanpH=7.5), yet which undergo hydrolysis at a more acidic pH range andwhich produce pleasant odors upon hydrolysis, are useful as thepotential fragrances or body activated fragrances of the composition ofthe present invention. Hereinafter, by acetals or ketals, useful in thepresent invention, we mean acetals, or ketals, of fragrance materialswhich exhibit the desired pH-dependent hydrolysis behavior and resultantodor (e.g., pleasant aroma) after hydrolysis. The composition can beapplied to the skin, using a suitable vehicle, and can achieve delayedrelease of fragrance (after application to the skin).

Another class of compounds useful as potential fragrances in the presentinvention are orthoesters. These orthoester compounds generally have theformula: ##STR1## where at least one of R₁, R₂, R₃ and R₄ is capable offorming a material having a fragrance upon hydrolysis of the orthoester.More specifically, (and illustratively, while not limiting), R₁ can beH, CH₃, phenethyl, cinnamyl, phenylpropyl, benzyl, santalyl, etc.; andR₂, R₃ and R₄ can be identical to each other or different, and can beCH₃, phenethyl, cinnamyl, phenylpropyl, benzyl, santalyl, etc. (R₂, R₃and R₄ cannot be H); however, if R₁ is CH₃ or H, then R₂, R₃ and R₄cannot all be CH₃ (that is, at least one of R₁ -R₄ must be phenethyl,cinnamyl, phenylpropyl, etc., i.e., a radical that forms a material witha fragrance upon hydrolysis). Thus, at least one of R₁ -R₄ must be aradical that forms a material with a fragrance upon hydrolysis.

The compounds as described in the foregoing can be utilized in thevarious personal care and skin care products as discussed in theforegoing, in the form of a solution, lotion, cream or other emulsion,gelled stick, aerosol, spray or liquid roll-on; and, in particular, canbe utilized to provide delayed release of fragrance in a transparent(clear) deodorant or antiperspirant stick product.

The composition of the present invention is an alkaline composition, or,if non-aqueous, is capable of providing an alkaline composition incontact with water. Hereinafter, when we refer to a composition capableof providing an alkaline composition when in contact with water, we meanboth (1) an alkaline composition (e.g., an alkaline compositioncontaining water) and (2) a composition which will be alkaline incontact with water (e.g., an anhydrous composition but which will bealkaline in contact with water). The compositions of the presentinvention are not acidic. In acidic compositions, the potentialfragrance would hydrolyze, releasing fragrance prior to application.

As is clear from the prior paragraph, the present invention does notrequire a water-based (or even water-containing) composition. Forexample, various powder compositions and gelled stick compositions fallwithin the present invention. Powders (e.g., baby powder, talcum powder)can be, for example, non-aqueous. Certain gelled sticks (e.g., stearylalcohol-cyclomethicone (Dow Corning Corp.)) are also non-aqueous.Moreover, compositions according to the present invention (e.g., clearor transparent compositions, such as clear or transparent stickcompositions) can contain relatively small amounts of water, e.g., about5% by weight. Such clear or transparent compositions containing 5% byweight water are illustrative, and such compositions can contain more orless than 5% by weight of water.

Since the composition according to the present invention is to bealkaline (or, if, e.g., non-aqueous, alkaline in contact with water orwater-containing substances), there is a need to ensure the presence ofwater-soluble, alkaline pH producing ingredients in any compositioncontaining any amount of water (or which will come into contact with anyamount of water prior to application). In this regard, a compositionwhich contains as little as 0.5% by weight water can cause some degreeof hydrolysis, especially if other polar solvents such as ethanol orpropylene glycol are present. Such water-soluble, alkaline pH producingingredients, commonly used in the art, include sodium bicarbonate,calcium or magnesium hydroxide, calcium or magnesium oxide, alkalineearth and alkali metal silicates, alkanolamines, tris (hydroxymethyl)aminomethane (TRIS buffer), sodium hydroxide, etc. Such water-soluble,alkaline pH producing ingredients can be used for either aqueous(water-containing) or non-aqueous compositions; however, for non-aqueouscompositions, powders such as sodium bicarbonate, magnesium oxide, etc.,are preferred.

The presently described potential fragrances can be used in non-acidicantiperspirant compositions, with antiperspirants that are alkaline innature (e.g., sodium aluminum lactate). However, presently usedantiperspirant compositions include antiperspirants that are acidic innature (e.g., aluminum chlorohydrate); the potential fragrance, if usedin such presently used antiperspirant compositions containing acidicantiperspirants, will not attain the objective of delayed release offragrance upon contact with, e.g., sweat.

In summary, according to one aspect of the present invention a"potential fragrance", which exhibits little or no odor when present inan alkaline composition, and is applied to human skin in an alkalinecomposition (or in a composition capable of producing an alkaline pHwhen in contact with water), hydrolyzes on human skin as the skin pH isnaturally lowered following alkaline insult due to application of thealkaline material to the skin. The resulting hydrolysis product, whichis odorous, imparts a pleasant smell to the skin. Again, the basis forthe hydrolyzing of the potential fragrance is the strong buffer capacityof the human skin to maintain a skin surface pH in the acidic range of5.5-7.0, depending upon skin and population, the skin buffer capacityneutralizing the alkalinity caused by the application of alkalinematerial to the skin and restoring normal pH (to thereby cause thehydrolysis).

Typically, several different potential fragrances (for example, severaldifferent carbonyl acetals or ketals) are compounded together into thealkaline formulation, to be applied to the skin, to ensure formulationof desirable "fragrances" or odors following hydrolysis on the skin.

In a further aspect of the present invention, sodium stearate-baseddeodorant sticks containing water, propylene glycol, monohydricalcohols, optionally other fragrances and colors, and includingpotential fragrances as discussed previously (including, specifically,orthoesters, and/or acetals or ketals of carbonyl compounds as discussedabove) can be provided to achieve delayed release of fragrance afterapplication to the skin, while still maintaining a transparent or cleardeodorant product.

Accordingly, by the present invention a product can be provided havingdelayed release of fragrance (e.g., a fragrancing product for contactwith human skin, such as a personal care or skin care product, can beprovided having delayed release of fragrance, delayed until aftercontact with the human skin; that is, a body activated fragrance),without the need of standard techniques for delayed release including,e.g., micro-encapsulation; moreover, the present invention enablesformation of a transparent (clear) deodorant or antiperspirant stickproduct having delayed release of fragrance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 demonstrate the pH-dependent hydrolysis of a specificorthoester.

FIGS. 3 and 4 demonstrate the pH-dependent hydrolysis of anotherspecific orthoester.

DETAILED DESCRIPTION OF THE INVENTION

While the invention will be described in connection with specific andpreferred embodiments, it will be understood that it is not intended tolimit the invention to those embodiments. On the contrary, it isintended to cover all alterations, modifications and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims.

Throughout the present description, where it is disclosed that thecomposition and method include or comprise specific materials or steps,it is also within the contemplation of the present invention that thecomposition or method consists essentially of, or consists of, therecited materials or steps.

The present invention contemplates a composition for delayed release offragrance; and in particular, a composition for application to the skinof a human (for example, a personal care product or skin care product),having potential fragrance components that are odorless or of a lowlevel of odor prior to application, but which change into a pleasantsmelling substance after contact with the skin (in particular, having abody activated release of fragrance). The composition is alkaline whenin contact with or containing water, and includes a vehicle and at leastone potential fragrance component (in addition to any other fragrancecomponents and/or other components such as coloring), the potentialfragrance component being odorless or of a low level of odor in alkalineconditions (an environment of pH of, for example, 9.5-10), yet whichhydrolyzes at lower pH to produce the pleasant smelling substance. Thedecrease in pH is achieved upon contact with the skin, which due to theskin's buffer capacity will neutralize the alkaline composition toprovide an environment for the potential fragrance component that willcause hydrolysis of the potential fragrance to produce the pleasantsmelling substance.

As indicated previously, various acetals or ketals, e.g., acetals orketals of carbonyl compounds, which are stable with respect tohydrolysis at alkaline pH (e.g., pH of greater than 8.0, preferably, pHgreater than 7.5) but which undergo hydrolysis at a more acidic pH, andwhich produce pleasant odors upon hydrolysis, are useful as thepotential fragrances or body activated fragrances incorporated in thecompositions of the present invention. Specific compounds useful aspotential fragrances according to the present invention are listed inthe following as Formulae I-IV. ##STR2##

Other such acetals or ketals that are hydrolyzable under more acidicconditions to form an odoriferous compound, but which are stable andhave little or no odor under more alkaline conditions, include(illustratively) citral butanetriol acetal, α-amyl cinnamaldehydedimethyl acetal, and α-amyl cinnamaldehyde butanetriol acetal.

Generally, the acetals and ketals that can be used according to thepresent invention include (but are not limited to) heliotropine polyolacetal, ionone dialkyl ketal, methyl naphthyl ketone dialkyl ketal,citral polyol acetal, α-amyl cinnamaldehyde dialkyl acetal, α-amylcinnamaldehyde polyol acetal, vanillin dialkyl acetal, vanillin alkyleneacetal, anisic aldehyde dialkyl acetal, anisic aldehyde polyol acetal,citral dialkyl acetal, and vanillin polyol acetal. Specific compoundswithin the scope of these acetals and ketals include ionone dimethylketal, ionone diethyl ketal, methyl naphthyl ketone dimethyl ketal,methyl naphthyl ketone diethyl ketal, citral ethylene glycol acetal,citral butanediol acetal, citral butanetriol acetal, citral propyleneglycol acetal, α-amyl cinnamaldehyde dimethyl acetal, α-amylcinnamaldehyde diethyl acetal, α-amyl cinnamaldehyde propylene glycolacetal, α-amyl cinnamaldehyde butanetriol acetal, α-amyl cinnamaldehydeethylene glycol acetal, vanillin dimethyl acetal, vanillin diethylacetal, vanillin ethylene acetal, vanillin propylene acetal anisicaldehyde dimethyl acetal, anisic aldehyde diethyl acetal, anisicaldehyde propylene glycol acetal, anisic aldehyde butanetriol acetal,anisic aldehyde ethylene glycol acetal, citral dimethyl acetal, citraldiethyl acetal, and vanillin propylene glycol acetal.

Illustratively, the acetals and ketals can be synthesized by a techniquewhich is a modification of the methods described in Organic SynthesesCollective Volume 3, pages 731-732. An example of this technique isshown in the following. Of course, such technique is illustrative andnot limiting.

A mixture of beta-methyl naphthyl ketone (200 g), trimethyl orthoformate(430 g) and toluene (250 ml) were stirred under nitrogen atmosphere for10 min. To this mixture, 1.8 ml of (47%) BF₃ OEt₂ was added and stirredfor 48 hours at room temperature, washed with aqueous NaHCO₃ andsaturated NaCl solution. The mixture was then dried over Na₂ SO₄,concentrated and distilled under reduced pressure to give 192 g ofbeta-methylnaphthylketone dimethyl ketal.

b.p. 113°-116° C./1.5mmHg

NMR(CDCl₃): 1.62(3H,s), 3.25(6H,s), 7.4-8.1(7H,m)

IR(neat): 3055, 1680, 1280

MS m/z: 184(M⁺ -MeOH)

Also, shown in the following are illustrations of the hydrolysisreactions which take place under acidic conditions, to release thepleasant smelling substances from the potential fragrances. The specificformulae for the following are the four above-listed compounds I-IV.##STR3##

The foregoing compounds and reactions are merely illustrative of variousacetal and ketal compounds, and fragrance materials formed therefrom,which can be utilized according to the present invention. In general,the acetals and/or ketals can be selected based upon the fragrancesdesired, and upon the following considerations to obtain a long-lastingfragrance. Thus, acyclic acetals hydrolyze faster than cyclic acetals.Acetals hydrolyze more quickly than ketals. Acetals formed fromshort-chain alcohols hydrolyze faster than acetals formed fromlonger-chain alcohols. Dimethyl acetals (DMA), diethyl acetals (DEA) andpropylene glycol acetals (PGA) generally hydrolyze quickly at a pH of 6(within the range of normal pH values of the skin); larger acetals willalso hydrolyze, but more slowly and at lower pH. Allylic conjugationwith the hydrolysis site results in faster hydrolysis thannon-conjugation. Electron-donating substituents on an aromatic ring withthe hydrolysis site increase the rate of hydrolysis. Andelectron-donating groups at the alpha position of an olefin conjugatedto the hydrolysis site decrease the rate of hydrolysis.

Not only can such acetals or ketals (e.g., acetals or ketals of carbonylcompounds, such as acetals or ketals of conjugated carbonyl compounds)be utilized, but also other compounds, including (but not limited to)esters, amides and hydrolyzable derivatives of carbonyl compounds,capable of producing pleasant odors, can be utilized according to thepresent invention.

As mentioned previously, another class of compounds useful as potentialfragrances in the present invention are orthoesters, generallyrepresented by the formula ##STR4## where at least one of R₁ -R₄ forms afragrance material upon hydrolysis of the orthoester. More specificdefinitions of R₁ -R₄ have previously been given.

In the following is set forth illustrative types of orthoester compoundsfor use in the present invention. These orthoester compounds areillustrative and not limiting, and show (particularly with theaforementioned acetals and ketals, esters, amides, etc.) the wide rangeof potential fragrances which can be used as part of the presentinvention. In the illustrative types of orthoesters in the following, R₁-R₄ refer to the R₁ -R₄ of the formula for orthoesters in theimmediately preceding paragraph. ##STR5## where R₄ can be phenethyl,cinnamyl, phenylpropyl, benzyl, geranyl, citronellyl, C-3-hexenyl andsantalyl; ##STR6## where R₁ can be phenyl, cinnamyl or benzyl; ##STR7##where R₂ -R₄ can be the same or different, and can be phenethyl,cinnamyl, phenylpropyl, benzyl, geranyl, citronellyl, C-3-hexenyl, andsantalyl (the same moieties for R as in the formulae Va and Vb).

The orthoesters can be synthesized by techniques known to those skilledin the art. Illustratively, an example of such techniques is shown inthe following. Of course, such technique is illustrative and notlimiting.

Synthesis of triethyl orthophenylacetate

To a mixture of dry ethanol (20 g) and dry chloroform (15 ml), 50 g ofbenzylnitrile was added and stirred at 10°-15° C. To this mixture, dryhydrochloride (15.6 g) was introduced. After 48 hours at roomtemperature, dry ethanol (100 ml) was added, and then left at roomtemperature for 2 days. The mixture was poured into a 5% NaOH solution.Then extraction was performed with chloroform and concentrated to givean oil (43 g). Triethyl orthophenylacetate was refined by distillation.(b.p 69°-71° C./1.5 mmHg, NMR(δ) 1.1-1.3(9H,m), 3.1(2H,s),3.5-3.6(6H,m), 7.2-7.4(5H,m)).

Also, shown in the following (E) and (F) are illustrations of thehydrolysis reactions which take place under acidic conditions, torelease the pleasant smelling substances from the orthoester potentialfragrances. The specific formulae for the following are theabove-described compounds Va, Vb, VI and VII. Also described in thefollowing are the fragrance materials formed, for a given R₄. ##STR8##Acid-hydrolyzed products of (E) and (F) are shown in the following TableA.

                  TABLE A                                                         ______________________________________                                        Identity of R.sub.4 in                                                        starting material                                                                        Hydrolysis Products                                                ______________________________________                                        Phenethyl  Rose P, Rose P acetate (formate)                                   Cinnamyl   Cinnamic alcohol, Cinnamyl acetate (formate)                       Phenylpropyl                                                                             Phenylpropyl alcohol                                                          Phenylpropyl acetate (formate)                                     Benzyl     Benzyl alcohol, Benzyl acetate (formate)                           Geranyl    Geraniol, Geranyl acetate (formate)                                Citronellyl                                                                              Citronellol, Citronellyl acetate (formate)                         c-3-Hexenyl                                                                              c-3-Hexenol, c-3-Hexenyl acetate (formate)                         Santalyl   Santalol, Santalyl acetate (formate)                                ##STR9##                                                                     Acid-hydrolyzed products of (G) are shown in the following                    Table B.                                                                      ______________________________________                                    

                  TABLE B                                                         ______________________________________                                        Identity of R.sub.1 in                                                        starting material Hydrolysis Products                                         ______________________________________                                        Phenyl            Methyl benzoate                                             Cinnamyl          Methyl cinnamate                                            Benzyl            Methyl phenylacetate                                         ##STR10##                                                                    R is the same as R.sub.2, R.sub.3 and R.sub.4 of Formula VII. Each R can      be                                                                            the same or different, and can be of any of the starting                      materials listed for "R.sub.4 " in Table A.                                   ______________________________________                                    

FIGS. 1 and 2 demonstrate the pH-dependent hydrolysis of a specificorthoester, where (in the general formula for orthoesters) R₁ =H, R₂=phenethyl, and R₃ =R₄ =CH₃. FIG. 2 shows that at pH=9.5, theconcentration of the specific orthoester, representing 90% of thecontents of a reaction mixture, is unchanged over a 24-hour period whilethe hydrolysis product, phenethyl alcohol, is unchanged over a 24-hourperiod at close to 0% of the reaction mixture. On the other hand, FIG. 1shows that at pH=6.5, the orthoester hydrolyzes rapidly and in about 9hours has essentially disappeared from the reaction mixture. Thefragrance material phenethyl alcohol has increased in concentration tocompletely replace the starting material. Thus, FIGS. 1 and 2demonstrate use of a specific orthoester as a potential fragrance,whereby at lower pH a material providing a fragrance is released fromthe orthoester.

FIGS. 3 and 4 demonstrate the pH-dependent hydrolysis of dimethylcis-3-hexenyl orthoformate, where (in the general formula fororthoesters) R₁ =H, R₂ =cis-3-hexenyl, and R₃ =R₄ =CH₃. FIG. 4 showsthat, at pH=8.6, and from a reaction mixture wherein the orthoesterrepresents 70-80% of the mixture, only a small percentage of theorthoester hydrolyzes over a 24-hour period, while the hydrolysisproduct, cis-3-hexenol, represents 0.-35% of the mixture after 24 hours.At a pH of 9 or higher, the concentration of hydrolysis product isunchanged over a 24-hour period, at close to 0% of the reaction mixture.On the other hand, FIG. 3 shows that at pH=6.5, the orthoesterhydrolyzes rapidly and in about 7 hours has essentially disappeared fromthe reaction mixture. Thus, FIGS. 3 and 4 demonstrate use of a differentorthoester, than the orthoester used in connection with FIGS. 1 and 2,as a potential fragrance, whereby at lower pH a material providing afragrance is released from the orthoester.

Various compositions, for contact with the skin, fall within the scopeof the present invention, including various skin care and personal careproducts. Based upon the specific vehicle utilized, the compositions areuseful as liquid roll-on compositions, powders, spray compositions,aerosol compositions, stick compositions and cream compositions, appliedto the human skin. For example, the compositions according to thepresent invention, utilizing a vehicle known in the art, and possiblyother components, including, e.g., water, to form an alkalinecomposition, can be used for underarm deodorants, hand lotions, babypowder, baby lotions, ointments, foot products, facial cleansers, bodywipes, facial make-up, colognes, after-shave lotions and shaving creams.

Apart from the incorporation of the potential fragrance as discussed inthe foregoing, and the necessity of an alkaline environment (e.g., analkaline vehicle) or an environment which becomes alkaline when incontact with water, the compositions according to the present inventioncan include conventional components which are used in conventionalcompositions, e.g., for liquid roll-ons, sprays, aerosols, creams andstick products. Thus, conventional components of various skin care andpersonal care products (e.g., stick deodorants, baby powders, handlotions, baby lotions, etc.) can also be incorporated within thecompositions according to the present invention, as long as suchcomponents do not so affect composition pH such that hydrolysis of thepotential fragrance occurs, and as long as such components are inert tothe potential fragrance (or as long as such components do not preventthe potential fragrance from releasing the pleasant smelling substanceby, e.g., hydrolysis after application of the composition to the skin).

Of course, the compositions according to the present invention caninclude conventional fragrances, as long as such fragrances are inert tothe potential fragrances of the present invention and do not so affectthe pH of the composition such that hydrolysis of the potentialfragrances occur.

The compositions according to the present invention can be manufacturedby techniques known in the art; and are applied in the same manner ascorresponding conventional compositions (e.g., conventional liquidroll-ons, sprays, aerosols, stick products and cream products).

The total concentration of potential fragrances in the compositionsaccording to the present invention illustratively may range from0.05%-3% by weight, although such concentration is not limited. Alsoillustratively (and not limiting), the potential fragrance may represent10%-100% of the total amount of fragrance ingredient in the composition.

As indicated previously, a plurality of potential fragrances (forexample, several carbonyl acetals or ketals) preferably are compoundedtogether in an alkaline formulation to ensure a formulation having adesirable set of "fragrances" or odors following hydrolysis, afterapplication to the skin.

As indicated previously, the present invention, incorporating potentialfragrances into compositions for contact with human skin, isparticularly appropriate in connection with stick deodorant orantiperspirant products that are clear or transparent. Suitableformulations include sodium stearate-based deodorant sticks containingwater, propylene glycol, monohydric alcohols, other fragrances, andcolor. However, the present invention is not limited to use of thepotential fragrances in clear or transparent stick compositions, andalso includes various compositions wherein solutions, lotions, creamsand other emulsions are used as vehicles for the composition (personalcare or skin care product) applied to the skin.

EXAMPLE 1

This example shows hydrolysis of various acetals or ketals of carbonylcompounds in acidic conditions, or in sweat with epidermal bacteria LT(arthrobacter species) and H6 (various of staphylococcus epidermidis),which acetals or ketals are stable under basic (alkaline) conditions.Hydrolysis of the various compounds was tested in sweat or water, asindicated.

The following four types of materials were tested for hydrolysis of theacetal or ketal:

(1) acetal in sweat or water;

(2) glucoside and ester in water;

(3) acetal and ketal by strain LT (or H6) in sweat (LT is Arthrobacters.p., and H6 is staphylococcus epidermis); and

(4) glucoside and ester with strain LT in sweat.

The procedure in connection with (1) and (2) above was as follows:

The pH of a mixture of acetal or ketal (300 μl), Nonipol 130 (SanyoKasei Co., Ltd.) (300 μl), Tween 80 (60 μl), and sweat (120 ml) or water(120 ml of distilled water) was regulated, and then the mixture wassterilized through a 0.45 μm micro filter. The sterilized mixture wasshaken for 24 hours at 37° C. The degree of hydrolysis was then checkedby gas chromatography using a dibenzyl compound as an internal standardafter 3, 6, 9 and 24 hours.

The procedure in connection with (3) and (4) of the foregoing was asfollows:

A mixture of acetal (or ketal) in an amount of 300 μl, Nonipol 130 (300μl), Tween 80 (60 μl) and sweat (120 ml) was sterilized through a 0.45μm micro filter. To the sterilized mixture, strain LT (or H6) was added,and the resultant mixture was shaken for 24 hours at 37° C. Theresulting material was checked by gas chromatography using a dibenzyl asan internal standard after 3, 6, 9 and 24 hours.

The results of the foregoing experiment are shown in the following Table1:

                  TABLE 1                                                         ______________________________________                                                                     REACTIVITY                                       COM-     ME-                 (% reacted)                                      POUND    DIA     PH      strain                                                                              3 hr 6 hr 9 hr 24 hr                           ______________________________________                                        Heliotropine                                                                           sweat   7.7-8.2 --    0    0    0    1.7                             ethylene water   7.2-7.9 --    0.4  3.6  5.6  11.0                            glycol acetal                                                                          sweat   7.6-8.0 LT    2.2  4.0  5.9  12.4                                     sweat   7.5-7.7 H6    1.5  3.0  5.7  16.2                                     sweat   6.2-6.4 --    18.1 32.4 40.7 64.7                                     water   5.7-5.8 --    63.8 65.7 66.7 68.5                            Ionone di-                                                                             sweat   7.6-7.8 --    2.4  19.0 32.8 25.9                            methyl ketal                                                                           water   6.7-7.1 --    18.8 30.6 33.5 28.3                                     sweat   7.4-7.6 LT    0.8  0.1  7.7  30.7                                     sweat   7.3-7.7 H6    18.5 18.1 16.0 28.8                                     sweat   6.4-6.6 --    36.4 45.8 44.8 29.1                                     water   6.9-7.0 --    13.0 14.8 28.8 13.8                            Methyl   sweat   7.7-8.1 --    0.0  0.0  2.5  12.4                            naphtyl  water   7.3-8.1 --    0.0  1.2  6.4  20.0                            ketone di-                                                                             sweat   7.6-7.8 LT    0.0  0.3  3.6  8.8                             methyl ketal                                                                           sweat   7.5-7.7 H6    1.1  5.8  7.6  20.5                                     sweat   6.3-6.4 --    26.1 40.2 50.1 83.3                                     water   6.2-6.4 --    54.4 75.8 87.9 93.7                            Citral butane-                                                                         sweat   6.9-7.3 --    1.5  6.9  10.3 14.6                            triol acetal                                                                           water   8.2-9.3 --    0.0  0.1  0.3  0.3                                      sweat   7.0-7.2 LT    4.3  7.5  12.1 20.8                                     sweat   7.5-7.9 H6    4.5  5.8  6.8  9.4                                      water   6.6-7.0 --    40.8 66.1 76.8 46.8                            α-Amyl                                                                           sweat   7.7-8.2 --    1.1  1.3  4.4  4.4                             cinnamalde-                                                                            water   7.2-8.0 --    0.0  0.0  1.0  3.3                             hyde di- sweat   7.5-7.7 LT    0.0  0.0  0.6  0.1                             methyl acetal                                                                          sweat   7.2-7.5 H6    0.0  0.4  0.5  0.6                                      sweat   6.3-6.4 --    10.5 11.5 21.9 24.6                                     water   3.5-6.2 --    5.9  12.9 22.1 36.6                            α-Amyl                                                                           sweat   7.8-8.2 --    3.2  3.4  3.9  0.6                             cinnamalde-                                                                            water   7.4-8.2 --    0.0  0.0  0.0  0.1                             hyde butane-                                                                           sweat   7.5-7.7 LT    0.8  0.1  0.1  0.3                             triol acetal                                                                           sweat   6.3-6.5 --    2.2  2.3  0.8  3.4                                      water   6.2-6.5 --    0.0  0.0  0.4  2.5                             Vanillin sweat   6.8-7.8 --    14.2 39.7 35.9 56.7                            propylene-                                                                             water   7.0-7.9 --    10.8 20.3 22.9 49.5                            glycol acetal                                                                          sweat   6.5-6.9 --    25.1 42.6 50.0 75.1                                     water   6.2-6.3 --    20.9 39.2 48.2 69.8                            Decanal  sweat   7.3-7.9 --    Not hydrolyzed                                 diethyl acetal                                                                         water   7.0-7.5 --                                                            sweat   6.5-6.9 --                                                            water   6.2-6.8 --                                                   Decanal  sweat   7.6-7.8 --    Not hydrolyzed                                 propylene-                                                                             water   7.5-8.3 --                                                   glycol acetal                                                                          sweat   7.5-7.7 LT                                                   C-3-Hexenyl                                                                            sweat   7.5-7.7 LT    Not hydrolyzed                                 glucoside                                                                              water   6.5-6.8                                                      Phenethyl                                                                              sweat   7.5-7.7 LT    Not hydrolyzed                                 acetate  water   6.0-7.0 --                                                   Geranyl  sweat   7.5-7.7 LT    Not hydrolyzed                                 acetate  water   6.0-7.0 --                                                   ______________________________________                                    

As can be seen in the foregoing Table 1, conjugated carbonyl compoundswere hydrolyzed in acidic water or in weak acidic sweat. More reactivearomatic compounds were. hydrolyzed even in basic (alkaline) conditions(under pH=8); but in more basic (alkaline) conditions (pH=8-9), acetalor ketal compounds were not hydrolyzed.

From the foregoing, it can be seen that acetals or ketals of variouscarbonyl compounds are hydrolyzed to original carbonyl compounds inacidic media (pH=6-7). Acetals or ketals of carbonyl aromatic compounds(vanillin, heliotropin and methyl naphthyl ketone) are hydrolyzed evenin mildly basic solutions; also, ionone dimethyl ketal and vanillinpropylene glycol acetal are hydrolyzed to ionone and vanillin both inacidic and basic conditions (pH=7-8); however, acetals or ketals ofcertain non-conjugated carbonyl compounds, and of esters and glucoside,are not hydrolyzed to the original compounds. In addition, the strainsLT and H6 cannot accelerate hydrolysis of acetal, ketal, glucoside andester in sweat or in water.

EXAMPLE 2

The pH of a mixture of Dimethyl phenyl orthoformate (0.3 g), Nonipol 130(0.5 g) and N-Cetane (0.1 g) as internal standard was regulated byphosphate buffer solution (50 ml), and then the mixture was shaken for24 hours at 37° C. The degree of hydrolysis was then checked by gaschromatography after 4, 9, and 24 hours. The conditions for the gaschromatography include the following:

column: OV-10.25 mm×25 m

temperature: 100°-220° (4°/min.)

The results are demonstrated as FIG. 3 and FIG. 4.

EXAMPLE 3

This example shows the results of hydrolyzing various acetals and ketalsat a pH of 6. The hydrolysis procedure used is described in thefollowing. A pH 6 phosphate buffer solution (Fisher) was preparedcontaining two nonionic surfactants (Igepal CO-720, 0.25% (Aldrich) andTween 80, 0.05% (Aldrich)) to ensure solubility of the potentialfragrances. To 5 ml of the pH 6 buffer was added a solution of 5 mg ofthe potential fragrance in 0.2 ml EtOAc and 20 μl of internal standardsolution (0.6M methyl stearate in EtOAc). The solution was stirred andincubated at 37° C., and 0.5 ml aliquots were removed periodically. Eachaliquot was extracted with 0.5 ml EtOAc, and 1 μl of the EtOAc layer wasanalyzed by gas chromatography (Hewlett Packard 5890 GC equipped with aFID and 12 m DB-5 capillary column). Quantitation of the hydrolysis wasperformed by monitoring the disappearance of the potential fragrance,relative to the internal standard.

The potential fragrances tested, are shown in Table 2. These potentialfragrances were purchased or synthesized as described in the following.

4-Butylbenzaldehyde DEA, benzaldehyde DMA, and hydroxycitronellal DMAwere obtained from Aldrich. Vanillin PGA was obtained from Pfaltz &Bauer, Inc. Amyl cinnamaldehyde DEA and DMA, anisaldehyde DEA and PGA,benzaldehyde PGA, citral DMA and PGA, decanal DEA, dodecanal DMA,heliotropin DEA, heridon, hyacinth DMA and GA (glyceryl acetal),hydratropic aldehyde DMA, isobutyl aldehyde DEA, laurinal DEA, leafacetal, nonanal DMA, talia, and troenan were provided by TakasagoInternational Corporation (Tokyo, Japan). All other acetals and ketalswere synthesized using the general procedures below.

Diethyl acetals.

Suzaral DEA.

To a THF (500 ml) solution of suzaral (115 mM) was added triethylorthoformate (172 mM) and a catalytic amount of p-toluenesulfonic acidmonohydrate (1.15 mM). The reaction flask was equipped with a Dean-Starktrap packed with 3 Å molecular sieves and refluxed until the reactionwas complete. Solvent and residual triethyl orthoformate were removed byrotary evaporation. Vacuum distillation (97° C., 400 mtorr) afforded acolorless oil (66% yield). Mass: [M]+ m/e 278. ¹ H-NMR (500 MHz, CDCl₃)δ0.87 (m,9H), 1.24 (m,6H), 1.84 (m,1H), 2.05 (m, 1H), 2.28 (d,2H), 2.44(d,2H), 3.50 (t,2H), 3.69 (t,2H), 4.20 (d,2H), 7.06 (m,4H).

Dupical DEA:

Colorless oil (87% yield). MS: [M]+ 278. ¹ H-NMR: δ0.93 (m,2H), 1.04(d,1H), 1.20 (2t,6H), (m, 1H), 1.65 (m,4H), 1.72 (t,1H), 1.85 (m,4H),1.95 (m, 1H), 2.05 (m,3H), 2.33 (s, 1/2H), 2.65 (s, 1/2H), 3.47 (m,2H),3.65 (m,2H), 4.47 (2t,1H) 4.95 (t, 1/2H), 5.17 (t, 1/2H).

Vanillin DEA:

Colorless oil (10% yield). MS: [M]+ 226. ¹ H-NMR: δ1.25 (t,6H), 3.55(m,2H), 3.65 (m,2H), 3.92 (s,3H), 5.4 (s,1H), 5.4 (s,1H), 6.88 (d,1H),6.95 (d,2H), 7.05 (s,1H).

Diethyl ketals.

Methyl naphthyl ketone DEK (diethyl ketal). To an ethanol (64 ml)solution of methyl naphthyl ketone (0.27M) was added triethylorthoformate (0.69M). An ethanol solution of hydrochloric acid (2.4M,1.2 ml) was added and the reaction was stirred at room temperature for 2days. Sodium ethoxide was added to quench the acid, followed byconcentration under vacuum. The acetal was filtered through carbon andcelite, washed with petroleum ether, and dried under high vacuum toafford a colorless oil (90% yield). MS:[M]+ 244. ¹ H-NMR: δ1.24 (t,6H),1.62 (s,3H), 3.47 (m,4H), 7.41 (m,2H), 7.6 (d,1H), 7.8 (m,3H), 8.05(s,1H).

Acetyl tetralin DEK:

Colorless oil (90% yield). MS: [M]+ 248. ¹ H-NMR: δ1.22 (t,6H), 1.52(s,3H), 1.78 (m,4H), 2.75 (m, 4H), 3.44 (m, 4H), 7.01 (d, 1H), 7.2 (m,2H).

Alpha ionone DEK:

Colorless oil (77% yield). MS: [M]+ 266. ¹ H-NMR: δ0.8 (s,3H), 0.9(s,3H), 1.15 (t,6H), 1.20-1.40 (m,2H), 1.38 (s,3H), 1.6 (s,3H), 2.0(m,2H), 2.05 (d,1H), 3.45 (m,4H), 5.4 (m,2H), 5.65 (dd, 1H).

Cyclic Acetals.

Heliotropin PGA.

To a THF (300 ml) solution of heliotropin (169 mmoles) was addedpropylene glycol (211.3 mM) and p-toluene sulfonic acid monohydrate(1.69 mM). The reaction flask was equipped with a Dean-Stark trap packedwith 3 Å molecular sieves and refluxed until complete. Afterconcentration under reduced pressure the crude acetal was vacuumdistilled (105° C., 450 millitorr), affording a colorless oil (75%yield). MS: [M]+ 208. ¹ H-NMR: δ1.34 (d, 3/2H), 1.39 (d,3/2H), 3.54(t,1/2H), 3.60 (t, 1/2H), 4.10 (t,1/2H), 4.26 (t,1/2H), 4.34 (dt,1H),5.72 (s,1/2H), 5.86 (s,1/2H), 5.96 (s,2H), 6.78 (d,1H), 6.96 (m,2H).

Decanal PGA:

Colorless oil (70% yield). MS:[M]+ 214. ¹ H-NMR: δ0.9 (t,3H), 1.3(m,14H), 1.65 (m,2H), 3.4 (m, 1H), 3.9 (t,1/2H), 4.18 (m,3/2H), 4.9(t,1/2H), 5.05 (t,1/2H).

Dodecanal PGA:

Colorless oil (68% yield). MS: [M]+ 242. ¹ H-NMR: δ0.9 (t,3H), 1.3(m,18H), 1.65 (m,2H), 3.4 (m, 1H), 3.9 (t,1/2H), 4.18 (m,3/2H), 4.9(t,1/2H), 5.05 (t,1/2H).

Dupical PGA:

Colorless oil (70% yield). MS:[M]+ 262. ¹ H-NMR: δ0.93 (m, 2H), 1.05 (d,1H), 1.19 (m, 1H), 1.25 (d,3/2H), 1.30 (d,3/2H), 1.41 (m, 1H), 1.68 (m,5H), 1.85 (m, 3H), 1.95-2.10 (m, 4H), 2.34 (s,1/2H), 2.68 (s,1/2H), 3.41(m, 1H), 3.93 (m, 1/2H), 4.12-4.22 (m,3/2H), 4.98 (m, 1H), 4.98 (m, 1H),5.20 (t,1/2H).

Heliotropin EGA:

Colorless oil (53% yield). MS: [M]+ 194. ¹ H-NMR: δ4.00 (m, 2H), 4.09(m, 2H), 5.71 (s, 1H), 5.96 (s,2H), 6.79 (m, 1H), 6.96 (m,2H).

Nonanal PGA:

Colorless oil (85% yield). MS: [M]+ 200. ¹ H-NMR: δ0.87 (t,3H), 1.3(m,12H), 1.64 (m,2H), 3.39 (m,1H), 3.93 (t,1/2H), 4.15 (m,3/2H), 4.89(t,1/2H), 5.0 (t,1/2H).

Suzaral PGA:

Colorless oil (85% yield). MS: [M]+ 262. ¹ H-NMR: δ0.88 (m,9H), 1.26(d,3/2H), 1.30 (d,3/2H), 1.83 (m, 1H), 2.0 (m, 1H), 2.35 (m, 1H), 2.43(d,2H), 2.85 (m, 1H), 3.40 (m, 1H), 3.96 (m,1/2H), 4.18 (m,3/2H), 4.81(d,1/2H), 4.89 (d,1/2H), 7.0 (m,4H).

The results of the hydrolysis are also shown in Table 2.

                  TABLE 2                                                         ______________________________________                                        Hydrolysis results                                                            Potential Fragrance                                                                            CAS Number Hydrolysis, pH 6                                  ______________________________________                                        4-butylbenzaldehyde diethyl                                                                    83803-80-9 none, 24 hr                                       acetal                                                                        anisaldehyde diethyl acetal                                                                    2403-58-9  100%, 1 hr                                        anisaldehyde propylene glycol                                                                  6414-32-0  80%, 8 hr                                         acetal                                                                        benzaldehyde dimethyl acetal                                                                   1125-88-8  90%, 7 hr                                         benzaldehyde propylene glycol                                                                  2568-25-4  none, 24 hr                                       acetal                                                                        vanillin diethyl acetal                                                                        85377-01-1 99%, 0.75 hr                                      vanillin propylene glycol                                                                      68527-74-2 89%, 6 hr                                         acetal                                                                        heliotropin diethyl acetal                                                                     40527-42-2 100%, 2 hr                                        heliotropin ethylene glycol                                                                    4405-18-9  64.7%, 24 hr                                      acetal                                                                        heliotropin propylene glycol                                                                   61683-99-6 84.8%, 48 hr                                      acetal                                                                        alpha ionone diethyl ketal                                                                     13743-48-1 95.1%, 24 hr                                      beta ionone diethyl ketal                                                                      13743-47-0 53.7%, 48 hr                                      beta methyl ionone diethyl                                                                     not registered                                                                           42.6%, 24 hr                                      ketal                                                                         dupical diethyl acetal                                                                         not registered                                                                           none, 45 hr                                       dupical propylene glycol                                                                       not registered                                                                           none, 48 hr                                       acetal                                                                        suzaral diethyl acetal                                                                         not registered                                                                           none, 45 hr                                       suzaral propylene glycol                                                                       not registered                                                                           none, 48 hr                                       acetal                                                                        amyl cinnamic aldehyde                                                                         60763-41-9 18%, 24 hr                                        diethyl acetal                                                                amyl cinnamic aldehyde                                                                         91-87-2    24.6%, 24 hr                                      dimethyl acetal                                                               decanal diethyl acetal                                                                         34764-02-8 none, 24 hr                                       decanal propylene glycol                                                                       5421-12-5  none, 24 hr                                       acetal                                                                        dodecanal dimethyl acetal                                                                      14620-52-1 none, 24 hr                                       dodecanal propylene glycol                                                                     82925-11-9 none, 48 hr                                       acetal                                                                        nonanal dimethyl acetal                                                                        18824-63-0 16%, 42 hr                                        nonanal propylene glycol                                                                       68391-39-9 none, 48 hr                                       acetal                                                                        methyl naphthyl ketone                                                                         not registered                                                                           60.1%, 48 hr                                      diethyl ketal                                                                 acetyl tetralin diethyl                                                                        not registered                                                                           91%, 48 hr                                        ketal                                                                         citral dimethyl acetal                                                                         7549-37-3  90%, 2 hr                                         citral propylene glycol                                                                        10444-50-5 66.4%, 24 hr                                      acetal                                                                        hyacinth dimethyl acetal                                                                       101-48-4   none, 45 hr                                       hyacinth glyceryl acetal                                                                       29895-73-6 none, 45 hi                                       hydratropic aldehyde dimethyl                                                                  90-87-9    none, 45 hr                                       acetal                                                                        hydroxycitronellal dimethyl                                                                    141-92-4   none, 24 hr                                       acetal                                                                        laurinal diethyl acetal                                                                        7779-94-4  27.8%, 45 hr                                      heridon          181-28-2   51%, 24 hr                                        intreleven aldehyde diethyl                                                                    not registered                                                                           none, 24 hr                                       acetal                                                                        isobutyl aldehyde diethyl                                                                      1741-41-9  87.1%, 45 hr                                      acetal                                                                        leaf acetal      28069-74-1 55.9%, 45 hr                                      talia            67633-92-5 14%, 42 hr                                        troenan          480-24-6   9%, 42 hr                                         ______________________________________                                    

The following conclusions can be drawn from these results. Acetalshydrolyze more quickly than ketals, and acyclic acetals hydrolyze morequickly than cyclic acetals. Acetals made from short-chain alcoholshydrolyze faster than acetals made from large alcohols. Dimethyl,diethyl and propylene glycol acetals generally hydrolyze quickly at a pHof 6; larger acetals will also hydrolyze, but more slowly and at a lowerpH. Allylic conjugation with the hydrolysis site results in fasterhydrolysis than hydrolysis of compounds with unsubstituted arylconjugation. Electron-donating substituents on an aromatic ring inconjugation with the hydrolysis site increase the rate of hydrolysis;and electron-withdrawing groups at the beta position of an olefinconjugated to the hydrolysis site decrease the rate of hydrolysis.

In the following are set forth examples of potential fragrancesincorporated in various products, according to the present invention. Inthe following examples, conventional methods of emulsification,gelation, co-solvency and mixing are used. The methods of forming thecompositions are well known in the art. In many cases, especially whenheating is required during processing, it is desirable to add thefragrances (regular or potential) last, to reduce fragrance loss due tovolatilization or decomposition.

    ______________________________________                                        Example A.                                                                    Water Based Gelled Deodorant Sticks                                                        % W/W                                                                         1    2      3      4    5    6                                   ______________________________________                                        Sodium Stearate                                                                              7.0    6.5    7.0  --   1.0  6.5                               DBMSA          --     --     --   1.5  1.5  --                                Magnesium Oxide                                                                              --     --     --   --   --   10.0                              Water          25.8   23.1   25.0 23.5 26.0 13.1                              Ethanol        --     --     --   --   --   10.0                              Propylene glycol                                                                             66.0   69.0   45.0 30.0 40.0 59.0                              Dipropylene glycol                                                                           --     --     19.5 31.2 21.2 --                                Sorbitol       --     --     --   3.5  3.5  --                                M-pyrol        --     --     --   5.0  4.0  --                                Dimethicone copolyol                                                                         --     --     --   4.0  --   --                                Triclosan.sup.∘                                                                  0.2    0.2    --   0.3  0.3  0.2                               PPG-3-Myristyl ether.sup.∘∘                                          --     --     2.0  --   1.0  --                                Potential Fragrance*                                                                         0.5    1.2    1.0  1.0  1.0  1.2                               Regular Fragrance**                                                                          0.5    --     0.5  --   0.5  --                                               100.0  100.0  100.0                                                                              100.0                                                                              100.0                                                                              100.0                             ______________________________________                                         .sup.∘ Vendor: Ciba Geigy                                         .sup.∘∘ Vendor: Croda Synthetic Chemicals Ltd.        *May be one or more potential fragrance ingredients                           **Fragrance of prior art  not a potential fragrance                      

The procedure is known to those skilled in the art. It is desirable toadd the fragrances last.

    ______________________________________                                        Example B.                                                                    Non-aqueous Gelled Deodorant Sticks                                                            % W/W                                                                         1     2                                                      ______________________________________                                        Stearyl Alcohol    21.0    16.0                                               Castorwax MP-70    --      4.0                                                PPG-15-stearyl ether                                                                             --      3.0                                                Glyceryl Monostearate                                                                            0.5     0.5                                                PEG-100            0.5     0.5                                                Cyclomethicone     60.5    57.5                                               Magnesium Oxide    15.0    --                                                 Sodium bicarbonate --      16.0                                               Potential fragrance                                                                              2.5     1.5                                                Regular fragrance  --      1.0                                                                   100.0   100.0                                              ______________________________________                                         Procedure:                                                                    Melt the stearyl alcohol and castorwax at 70-80° C. While stirring     add the glyceryl monostearate, PEG100 and PPG15 stearyl ether. While          cooling, add the cyclomethicone and maintain at 55-60° C. Add the      magnesium oxide or sodium bicarbonate. While stirring add the fragrances      last and cool.                                                           

    ______________________________________                                        Example C.                                                                    Water-based Roll-on Deodorants                                                            % W/W                                                                         1      2       3        4                                         ______________________________________                                        Water         44       45      73     78.0                                    Cyclomethicone                                                                              33       30      --     --                                      Magnesium Oxide                                                                             15       --      15     5.0                                     Sodium bicarbonate                                                                          --       15      --     --                                      Sodium silicate                                                                             --       --      --     5.0                                     Dinethicone copolyol.sup.∘                                                       5        6      --     --                                      (10% active)                                                                  Polysorbate 20.sup.∘∘                                                1        2      --     --                                      PPG-15 Stearyl ether                                                                        --       --      5.0    5.0                                     Steareth-2.sup.∘∘∘                                      --       --      1.5    1.5                                     Steareth-78.sup.∘∘∘∘                        --       --      3.5    3.5                                     Potential Fragrance                                                                         1.5      1.0     2.0    2.0                                     Regular Fragrance                                                                           0.5      1.0     --     --                                                    100.0    100.0   100.0  100.0                                   ______________________________________                                         .sup.∘ Vendor: Dow Corning Ltd.                                   .sup.∘∘ Vendor: Emery Industries Inc.                 .sup.∘∘∘ Vendor: Brooks & Perkin Inc.     .sup.∘∘∘∘ Vendor: Brooks      Perkin Inc.                                                              

    ______________________________________                                        Example D.                                                                    Suspension Deodorant Roll-Ons                                                                  % W/W                                                                         1     2                                                      ______________________________________                                        Cyclomethicone     66.5    74.0                                               Bentone            2.5     2.5                                                SD-40 Alcohol      1.0     1.0                                                Magnesium Oxide    18.0    --                                                 Sodium bicarbonate --      15.0                                               Dimethicone        10.0    --                                                 Isopropyl myristate                                                                              --      5.0                                                Potential fragrance                                                                              2.0     1.5                                                Regular fragrance  --      1.5                                                                   100.0   100.0                                              ______________________________________                                    

    ______________________________________                                        Example E.                                                                    Powder Compositions                                                                      % W/W                                                                         1      2        3        4                                         ______________________________________                                        Talc         89.0     73.0     81.0   56.0                                    Cornstarch   --       15.0     --     30.0                                    Magnesium Oxide                                                                            5.0      --       --                                             Sodium bicarbonate                                                                         --       10.0     --     4.0                                     Calcium silicate                                                                           --       --       2.0    --                                      Oatmeal      2.0      --       15.0   5.0                                     Potential fragrance                                                                        2.0      1.0      1.5    3.0                                     Regular fragrance                                                                          1.0      1.0      0.5    --                                      Dimethicone  1.0      --       --     2.0                                                  100.0    100.0    100.0  100.00                                  ______________________________________                                    

    ______________________________________                                        Example F.                                                                    Baby Lotions                                                                         % W/W                                                                         1         2           3                                                ______________________________________                                        Oil Phase                                                                     Glyceryl 1.5         1.0         0.7                                          stearate                                                                      Isopropyl                                                                              1.5         1.0         1.3                                          palmitate                                                                     Lauramine.sup.∘                                                            0.5         0.5         0.5                                          Mineral oil                                                                            1.5         1.0         1.0                                          Stearic Acid                                                                           0.8         0.8         1.0                                          Cetyl    0.7         0.8         0.7                                          Alcohol                                                                       Propyl   0.1         0.1         0.1                                          paraben                                                                       Potential                                                                              1.3         1.0         1.5                                          fragrance                                                                     Regular  0.3         0.5         --                                           fragrance                                                                     Water Phase                                                                   Propylene                                                                              2.0         2.0         2.0                                          glycol                                                                        Carbomer --          0.1         --                                           934                                                                           Trimethamine                                                                           1.0         0.8         1.2                                          Tetrasodium                                                                            0.5         0.5         0.6                                          EDTA                                                                          Sodium   q.s. to pH = 8.2                                                                          --          q.s. pH = 8.5                                hydroxide                                                                     Triethanol-                                                                            --          q.s. to pH = 8.0                                                                          0.5                                          amine                                                                         Water    q.s. to 100.0                                                                             q.s. to 100.0                                                                             q.s. to 100.0                                ______________________________________                                         .sup.∘ Vendor: Akzo NV NL                                          Procedure:                                                                   Heat water to 70° C. Add other water phase ingredients, adding the     triethanolamine and/or sodium hydroxide last. Separately melt the content     of the oil phase together, then add the oil phase to the water phase with     agitation. Cool to set point and fill.                                   

    ______________________________________                                        Example G.                                                                    Skin or Body Creams                                                                          % W/W                                                                         1       2                                                      ______________________________________                                        Oil Phase                                                                     Glyceryl Stearate                                                                              5.0       5.5                                                Isopropyl Myristate                                                                            3.0       3.5                                                Stearic Acid     2.5       2.0                                                Propyl paraben   0.1       0.1                                                Potential fragrance                                                                            1.5       0.7                                                Regular fragrance                                                                              --        0.7                                                Water Phase                                                                   Glycerine        6.0       6.0                                                Triethanalamine  1.0       1.0                                                Methyl paraben   0.2       0.2                                                Tetrasodium EDTA 0.5       --                                                 Magnesium Oxide  3.0       3.5                                                Water            q.s. to 100.0                                                                           q.s. to 100.0                                      ______________________________________                                         Procedure similar to Baby Lotions                                        

    ______________________________________                                        Example H.                                                                    Ointments                                                                                 % W/W                                                                         1        2       3                                                ______________________________________                                        Zinc Oxide    20.0       25.0    12.0                                         Magnesium Oxide                                                                             --         --       8.0                                         Mineral Oil   15.0       --      12.0                                         White Ointment                                                                              63.0       --      61.5                                         White Petrolatum                                                                            --         50.0    --                                           Starch        --         23.0     5.0                                         Potential fragrance                                                                          2.0        1.0     1.0                                         Regular fragrance                                                                           --          1.0     0.5                                                       100.0      100.0   100.0                                        ______________________________________                                    

    ______________________________________                                        Example I.                                                                    After-Shave Lotions and Colognes                                                               % W/W                                                                         1     2                                                      ______________________________________                                        Propylene glycol   2.0     2.0                                                Ethanol            75.0    80.0                                               Water              16.5    9.3                                                Sodium bicarbonate 2.0     2.0                                                Sodium hydroxide   0.2     --                                                 Tetrasodium EDTA   0.5     0.5                                                Benzophenone - 4.sup.∘                                                               0.3     0.2                                                Potential fragrance                                                                              2.0     2.0                                                Regular fragrance  1.5     4.0                                                                   100.0   100.0                                              ______________________________________                                         .sup.∘ Vendor: BASF AG                                       

    ______________________________________                                        Example J.                                                                    Aerosol Deodorant Compositions                                                                   1     2                                                    ______________________________________                                        Benzethonium chloride                                                                              0.21    --                                               Dipropylene glycol   1.00    --                                               SDA-40 Alcohol (anhydrous)                                                                         65.00   0.75                                             Potential fragrance  1.50    1.50                                             Regular fragrance    0.50    --                                               Hydrocarbon A-46 propellant                                                                        --      74.00                                            Hydrocarbon A-70 propellant                                                                        31.40   --                                               Trimethamine         0.39    --                                               Cyclomethicone       --      12.00                                            Isopropyl myristate  --      4.00                                             Magnesium oxide      --      7.00                                             Bentone 38           --      0.75                                                                  100.0   100.00                                           ______________________________________                                    

    ______________________________________                                        Example K.                                                                    Shaving Creams                                                                                % w/w                                                         ______________________________________                                        Stearic Acid      8.5                                                         Triethanolamine   3.0                                                         Potassium hydroxide                                                                             1.0                                                         Polysorbate 20    1.2                                                         Glycerin          2.2                                                         Lauramide DEA     0.8                                                         Isopropyl myristate                                                                             0.5                                                         Water             79.3                                                        A-46 Propellant   3.5                                                                           100.0                                                       ______________________________________                                    

Accordingly, by the present invention, a composition, e.g., forapplication to the skin, containing a potential fragrance (that is, bodyactivated fragrance, which under alkaline conditions has little or noodor but which releases a fragrance compound by hydrolysis, under acidicconditions, e.g., on the skin), achieves a delayed release of fragrance.By incorporating such potential fragrance in a sodium stearate-baseddeodorant or antiperspirant stick product, a transparent or cleardeodorant or antiperspirant stick product can be achieved.

While we have shown and described several embodiments in accordance withthe present invention, it is understood that the same is not limitedthereto, but is susceptible to numerous changes and modifications as areknown to one having ordinary skill in the art, and we therefore do notwish to be limited to the details shown and described herein, but intendto cover all such modifications as are encompassed by the scope of theappended claims.

We claim:
 1. A composition for application to the skin, the composition being capable of producing an alkaline pH when in contact with water and including (1) a vehicle such that when the composition is in contact with water, the composition is at the alkaline pH, and (2) at least one potential fragrance, the at least one potential fragrance being at least one compound having a first level of aroma in the composition, and reacting when in contact with the skin to respectively produce a compound having a fragrance, the fragrance being of a second level of aroma, the second level being stronger than the first level, wherein the at least one potential fragrance is selected from the group consisting of heliotropine ethylene glycol acetal, ionone dialkyl ketal, methyl naphthyl ketone dialkyl ketal, citral polyol acetal, α-amyl cinnamaldehyde dialkyl acetal, α-amyl cinnamaldehyde polyol acetal, vanillin dialkyl acetal, vanillin alkylene acetal, anisic aldehyde dialkyl acetal, anisic aldehyde polyol acetal, citral dialkyl acetal, and vanillin polyol acetal.
 2. The composition according to claim 1, wherein said at least one potential fragrance does not undergo hydrolysis at a pH level greater than 7.5 and undergoes hydrolysis at a pH of 7.5 or less.
 3. The composition according to claim 1, wherein said at least one potential fragrance includes a plurality of potential fragrances, each being a compound selected from said group, the plurality of potential fragrances providing, in combination, after said reacting, compounds producing a combination fragrance.
 4. The composition according to claim 1, wherein the ionone dialkyl ketal is ionone dimethyl ketal or ionone diethyl ketal; the methyl naphthyl ketone dialkyl ketal is methyl naphthyl ketone dimethyl ketal or methyl naphthyl ketone diethyl ketal; the citral polyol acetal is selected from the group consisting of citral ethylene glycol acetal, citral butanediol acetal, citral butanetriol acetal and citral propylene glycol acetal; the α-amyl cinnamaldehyde dialkyl acetal is α-amyl cinnamaldehyde dimethyl acetal or α-amyl cinnamaldehyde diethyl acetal; the α-amyl cinnamaldehyde polyol acetal is selected from the group consisting of α-amyl cinnamaldehyde propylene glycol acetal, α-amyl cinnamaldehyde butanetriol acetal and α-amyl cinnamaldehyde ethylene glycol acetal; the vanillin dialkyl acetal is vanillin dimethyl acetal or vanillin diethyl acetal; the vanillin alkylene acetal is vanillin ethylene acetal or vanillin propylene acetal; the anisic aldehyde dialkyl acetal is anisic aldehyde dimethyl acetal or anisic aldehyde diethyl acetal; the anisic aldehyde polyol acetal is selected from the group consisting of anisic aldehyde propylene glycol acetal, anisic aldehyde butanetriol acetal and anisic aldehyde ethylene glycol acetal; and the citral dialkyl acetal is citral dimethyl acetal or citral diethyl acetal; and the vanillin polyol acetal is vanillin propylene glycol acetal.
 5. The composition according to claim 1, wherein said at least one potential fragrance is included in the composition in an amount of 0.05% to 3% by weight of the total weight of the composition.
 6. The composition according to claim 1, wherein the at least one potential fragrance is included in the composition in an amount of 10% to 100% by weight of the total amount of fragrance components in the composition.
 7. The composition according to claim 1, wherein said vehicle is a vehicle for forming a liquid roll-on composition, whereby the composition can be applied to the skin as a roll-on.
 8. The composition according to claim 1, wherein said vehicle is a vehicle for forming a stick deodorant composition, whereby the composition can be applied to the skin as a stick product.
 9. The composition according to claim 8, wherein the stick deodorant composition is a transparent composition containing said at least one potential fragrance.
 10. The composition according to claim 9, wherein the stick deodorant composition includes, as said vehicle, sodium stearate as a gelling agent, whereby the transparent stick deodorant composition is a sodium stearate based stick deodorant.
 11. The composition according to claim 10, wherein the stick deodorant composition further includes water, propylene glycol and monohydric alcohols.
 12. The composition according to claim 1, wherein the vehicle is a powder, whereby the composition can be applied to the skin as a powder.
 13. The composition according to claim 1, wherein said vehicle is a vehicle for forming a baby lotion, wherein the composition is a baby lotion.
 14. The composition according to claim 1, wherein said vehicle is a vehicle for forming an after-shave lotion, whereby the composition is an after-shave lotion.
 15. The composition according to claim 1, wherein the composition includes water.
 16. A composition for imparting a fragrance, the composition being capable of producing an alkaline pH when in contact with water and including (1) a vehicle such that when the composition is in contact with water, the composition is at an alkaline pH, and (2) at least one potential fragrance, the at least one potential fragrance being at least one compound having a first level of aroma in the composition at the alkaline pH, but reacting in a more acidic environment than the alkaline pH to produce a compound having a fragrance, the fragrance being of a second level of aroma that is stronger than the first level, wherein the at least one potential fragrance is selected from the group consisting of heliotropine ethylene glycol acetal, ionone dialkyl ketal, methyl naphthyl ketone dialkyl ketal, citral polyol acetal, α-amyl cinnamaldehyde dialkyl acetal, α-amyl cinnamaldehyde polyol acetal, vanillin dialkyl acetal, vanillin alkylene acetal, anisic aldehyde dialkyl acetal, anisic aldehyde polyol acetal, citral dialkyl acetal, and vanillin polyol acetal.
 17. The composition according to claim 16, wherein the composition has a pH greater than 8.0 when in contact with water, and wherein the at least one potential fragrance is at least one compound that is hydrolyzed at a pH of at most 8.0 to produce the compound having the fragrance of the second level of aroma.
 18. A method of providing a fragrance, comprising the steps of:(a) applying a fragrancing composition, the fragrancing composition being capable of producing an alkaline composition when in contact with water and including (1) a vehicle such that when the composition is in contact with water, the composition is at an alkaline pH, and (2) at least one potential fragrance, the at least one potential fragrance being at least one compound having a first level of aroma in the alkaline composition, prior to application, and producing at least one compound with a fragrance, the fragrance being of a second level of aroma, stronger than the first level, when in a more acidic environment than the alkaline pH, wherein the at least one potential fragrance is selected from the group consisting of heliotropine ethylene glycol acetal, ionone dialkyl ketal, methyl naphthyl ketone dialkyl ketal, citral polyol acetal, α-amyl cinnamaldehyde dialkyl acetal, α-amyl cinnamaldehyde polyol acetal, vanillin dialkyl acetal, vanillin alkylene acetal, anisic aldehyde dialkyl acetal, anisic aldehyde polyol acetal, citral dialkyl acetal, and vanillin polyol acetal; and (b) lowering the pH of an environment of the at least one potential fragrance, after application, so as to produce said at least one compound with the fragrance, of the second level of aroma.
 19. The method according to claim 18, wherein the fragrancing composition is applied to skin of a human, and wherein the pH of the environment is lowered by the natural buffering capacity of the skin to maintain a skin surface pH of 5.5-7.0.
 20. The method according to claim 19, wherein the fragrancing composition is a stick deodorant, the stick deodorant being applied to the skin in the axillary region.
 21. A composition for application to the skin, the composition being capable of producing an alkaline pH when in contact with water and including (1) a vehicle such that when the composition is in contact with water, the composition is at the alkaline pH, and (2) at least one potential fragrance, the at least one potential fragrance being at least one compound having a first level of aroma in the composition, and reacting when in contact with the skin to respectively produce a compound having a fragrance, the fragrance being of a second level of aroma, the second level being stronger than the first level, wherein the at least one potential fragrance is selected from the group consisting of anisaldehyde diethyl acetal, anisaldehyde propylene glycol acetal, benzaldehyde dimethyl acetal, vanillin diethyl acetal, vanillin propylene glycol acetal, heliotropin diethyl acetal, heliotropin ethylene glycol acetal, alpha ionone diethyl ketal, beta ionone diethyl ketal, beta methyl ionone diethyl ketal, amyl cinnamic aldehyde diethyl acetal, amyl cinnamic aldehyde dimethyl acetal, nonanal dimethyl acetal, methyl naphthyl ketone diethyl ketal, acetyl tetralin diethyl ketal, citral dimethyl acetal, citral propylene glycol acetal, laurinal diethyl acetal, heridon, isobutyl aldehyde diethyl acetal, leaf acetal, talia and troenan.
 22. The composition according to claim 21, wherein said at least one potential fragrance does not undergo hydrolysis at a pH level greater than 7.5 and undergoes hydrolysis at a pH of 7.5 or less.
 23. The composition according to claim 21, wherein said at least one potential fragrance includes a plurality of potential fragrances, each being a compound selected from said group, the plurality of potential fragrances providing, in combination, after said reacting, compounds producing a combination fragrance.
 24. The composition according to claim 21, wherein said at least one potential fragrance is included in the composition in an amount of 0.05% to 3% by weight of the total weight of the composition.
 25. The composition according to claim 21, wherein the at least one potential fragrance is included in the composition in an amount of 10% to 100% by weight of the total amount of fragrance components in the composition.
 26. The composition according to claim 21, wherein said vehicle is a vehicle for forming a liquid roll-on composition, whereby the composition can be applied to the skin as a roll-on.
 27. The composition according to claim 21, wherein said vehicle is a vehicle for forming a stick deodorant composition, whereby the composition can be applied to the skin as a stick product.
 28. The composition according to claim 21, wherein the vehicle is a powder, whereby the composition can be applied to the skin as a powder.
 29. The composition according to claim 21, wherein said vehicle is a vehicle for forming a baby lotion, whereby the composition is a baby lotion.
 30. The composition according to claim 21, wherein said vehicle is a vehicle for forming an after-shave lotion, whereby the composition is an after-shave lotion.
 31. The composition according to claim 21, wherein the composition includes water.
 32. A composition for imparting a fragrance, the composition being capable of producing an alkaline pH when in contact with water and including (1) a vehicle such that when the composition is in contact with water, the composition is at an alkaline pH, and (2) at least one potential fragrance, the at least one potential fragrance being at least one compound having a first level of aroma in the composition at the alkaline pH, but reacting in a more acidic environment than the alkaline pH to produce a compound having a fragrance, the fragrance being of a second level of aroma that is stronger than the first level, wherein the at least one potential fragrance is selected from the group consisting of anisaldehyde diethyl acetal, anisaldehyde propylene glycol acetal, benzaldehyde dimethyl acetal, vanillin diethyl acetal, vanillin propylene glycol acetal, heliotropin diethyl acetal, heliotropin ethylene glycol acetal, alpha ionone diethyl ketal, beta ionone diethyl ketal, beta methyl ionone diethyl ketal, amyl cinnamic aldehyde diethyl acetal, amyl cinnamic aldehyde dimethyl acetal, nonanal dimethyl acetal, methyl naphthyl ketone diethyl ketal, acetyl tetralin diethyl ketal, citral dimethyl acetal, citral propylene glycol acetal, laurinal diethyl acetal, heridon, isobutyl aldehyde diethyl acetal, leaf acetal, talia and troenan.
 33. The composition according to claim 32, wherein the composition has a pH greater than 8.0 when in contact with water, and wherein the at least one potential fragrance is at least one compound that is hydrolyzed at a pH of at most 8.0 to produce the compound having the fragrance of the second level of aroma.
 34. A method of providing a fragrance, comprising the steps of:(a) applying a fragrancing composition, the fragrancing composition being capable of producing an alkaline composition when in contact with water and including (1) a vehicle such that when the composition is in contact with water, the composition is at an alkaline pH, and (2) at least one potential fragrance, the at least one potential fragrance being at least one compound having a first level of aroma in the alkaline composition, prior to application, and producing at least one compound with a fragrance, the fragrance being of a second level of aroma, stronger than the first level, when in a more acidic environment than the alkaline pH, wherein the at least one potential fragrance is selected from the group consisting of anisaldehyde diethyl acetal, anisaldehyde propylene glycol acetal, benzaldehyde dimethyl acetal, vanillin diethyl acetal, vanillin propylene glycol acetal, heliotropin diethyl acetal, heliotropin ethylene glycol acetal, alpha ionone diethyl ketal, beta ionone diethyl ketal, beta methyl ionone diethyl ketal, amyl cinnamic aldehyde diethyl acetal, amyl cinnamic aldehyde dimethyl acetal, nonanal dimethyl acetal, methyl naphthyl ketone diethyl ketal, acetyl tetralin diethyl ketal, citral dimethyl acetal, citral propylene glycol acetal, laurinal diethyl acetal, heridon, isobutyl aldehyde diethyl acetal, leaf acetal, talia and troenan; and (b) lowering the pH of an environment of the at least one potential fragrance, after application, so as to produce said at least one compound with the fragrance, of the second level of aroma.
 35. The method according to claim 34, wherein the fragrancing composition is applied to skin of a human, and wherein the pH of the environment is lowered by the natural buffering capacity of the skin to maintain a skin surface pH of 5.5-7.0. 